Opposition figures are gathering in Turkey to debate how they can break the rule of the Syrian president, Bashar al-Assad. Photograph: Benoit Tessier/Reuters

Key business figures in Syria are aligning themselves with opposition groups before a conference in Turkey on Tuesday in a sign that Syria's traditionally pro-regime business elite may be beginning to break ranks with the government of President Bashar al-Assad.

About 300 opposition figures are expected to arrive in Antalya, southern Turkey, for the three-day Syrian Conference for Change, designed to establish dialogue between opposition groups with a view to establishing a transitional council.

However, as a bloody crackdown against anti-regime protests continued, with Syrian activists reporting troops had bombarded a town in the central province of Homs with artillery on Sunday, it is clear sharp divisions exist among the fledgling opposition.

Until now, the Syrian uprising has largely manifested itself at street level with support from activists abroad as disaffected and marginalised classes call for personal freedoms and an end to corruption and poverty at the hands of the elite.

Organised by the Egypt-based National Organisation for Human Rights, the Turkey conference is being privately funded by three Syrian businessmen – Ali and Wassim Sanqar, brothers who are luxury car distributors based in Damascus, and Ammar Qurabi, chairman of the national organisation and UAE-based satellite channel Orient TV.

Orient TV's Damascus bureau was closed after a bid to forcefully buy out the channel by the president's cousin Rami Makhlouf, who is on the US sanctions list and controls an estimated 60% of the Syrian economy through stakes in various companies.

The Sanqar brothers also ran up against Makhlouf when a law was changed allowing him to acquire sole distribution rights for their company's lucrative Mercedes dealership.

The Sanqar brothers declined to comment on their role at the conference, but Ammar Abdulhamid, the exiled Syrian dissident and head of the Washington-based Tharwa Foundation, said the inclusion of business personalities was "a significant development".

"We have a number of other businessmen and entrepreneurs here. The business community is slowly coming around to realising the need to support the future of Syria," he said.

On the eve of the conference, divisions were apparent. Organisers admitted they were rushed. Others, while calling for unity, privately complained of inadequate planning and consultation. Kurdish groups are boycotting the conference.

In London, an exiled nephew of the president claimed the conference was a front for Islamist extremism. Ribal al-Assad, head of the London-based Organisation for Democracy and Change, announced he would hold an alternative conference based on "freedom, democracy and religious pluralism".

The son of Rifat al-Assad, who led the 1982 Hama massacre of up to 20,000 people following an uprising by the Muslim Brotherhood, has attracted the ire of dissidents after failing to acknowledge his father's role in the siege.

"I can assure you that none of these people represents the Syrian opposition," he said. "They are individuals that only represent themselves."

He said some former brotherhood members were posing as moderates.

Long suspected of holding political ambitions, Assad said his only personal role was to "play a small part in bringing freedom, democracy and human rights to my country".

A pro-democracy activist and organiser, Radwan Ziadeh from the National Initiative for Change, denied the claims, saying the conference represented both secular and moderate Islamic groups.

But he acknowledged the need for religious Syrian society to be present. "We know Syrian society is very conservative. Moderate Muslims must be present."

He said leadership alternatives in Syria had been repressed. "Everyone knows that the Syrian uprising is leaderless. We need to establish some sort of balance to move ahead.

"The intended outcome is for a united opposition established on the principles of greater co-ordination inside and outside Syria."

He stressed that although Turkey sanctioned the conference, no state representatives would be present but said that any party formed should seek assistance from the Arab League and other international organisations.

"We can divide the cake later on, for now the focus is on the humanitarian issue in putting pressure on regime that has killed over 1,100 people and detained more than 11,000."